Abstract

Perceiving the geometry of surrounding space is a multisensory process, crucial to contextualizing object perception and guiding navigation behavior. Humans can make judgments about surrounding spaces from reverberation cues, caused by sounds reflecting off multiple interior surfaces. However, it remains unclear how the brain represents reverberant spaces separately from sound sources. Here we report separable neural signatures of auditory space and source perception during magnetoencephalography (MEG) recording as subjects listened to brief sounds convolved with monaural room impulse responses. The decoding signature of sound sources began at 57 ms after stimulus onset and peaked at ∼130 ms, while space decoding started at 138 ms and peaked at 386 ms. Importantly, these neuromagnetic responses were readily dissociable in form and time: while sound source decoding exhibited an early and transient response, the neural signature of space was sustained and independent of the original source that produced it. The reverberant space response was robust to variations in sound source, and vice versa, indicating a generalized response not tied to specific source-space combinations. These results provide the first neuromagnetic evidence for robust, dissociable auditory source and reverberant space representations in the human brain and reveal the temporal dynamics of how auditory scene analysis extracts percepts from complex naturalistic auditory signals.

Significance Statement We often unconsciously process echoes to help navigate places or localize objects. However, very little is known about how the human brain performs auditory space analysis, and in particular, segregates direct sound source information from the mixture of reverberant echoes that characterize the surrounding environment. Here we used MEG to characterize the time courses of auditory source and space perception in the human brain. We found that the brain responses to spatial extent in reverberant environments were separable from those to the sounds that produced the reverberations, and robust to variations in those sounds. Our results demonstrate the existence of dedicated neural mechanisms that separately process auditory reverberations and source within the first few hundred milliseconds of hearing.

Footnotes

Authors report no conflicts of interest.

This work was funded by National Eye Institute grant EY020484 (to A.O.), the Vannevar Bush Faculty Fellowship program sponsored by the Basic Research Office of the Assistant Secretary of Defense for Research and Engineering and funded by the Office of Naval Research through grant N00014-16-1-3116 (to A.O.), and the McGovern Institute Neurotechnology Program (to A.O. and D.P.).